AUGER AND X-RAY ABSORPTION STUDIES OF SOLID MOLECULAR-OXYGEN

We have studied the x-ray absorption spectrum (XAS) and the Auger electron spectrum (AES) of condensed molecular oxygen in the vicinity of the O Is (K) core level. The XAS spectrum, which is similar to that previously reported for gas phase 02,has sharp peaks at about 530.8 and 540.3 eV, which we attribute to excitations from the Is level into π* and σ* states, respectively. We assign a third peak at 543.3 eV to Rydberg transitions. Compared with gas phase O2, the σ* and Rydberg states are shifted to higher energies, an effect that we attribute to solid state effects in the condensed layer. The AES spectra of the ionized molecule and excited molecule are both shifted relative to the spectra of gas phase O2, but by different amounts, 10 and 2 eV, respectively, which may be due to different final state screening effects. A tentative assignment of the features in the AES spectra is also made. © 1990, American Vacuum Society. All rights reserved.